Method and Apparatus for Performing Joint Channel and Time Estimation in a Gnss Receiver

2. The receiver of claim 1, wherein the signals received over the respective channels include contributions from one or more of the navigation signals.

3. The receiver of claim 2, wherein the receiver is configured to detect a given navigation signal included in a signal received over a given channel based on the calculated cross-correlation function between the signal received over the given channel and the reference version of the given navigation signal.

4. The receiver of claim 3, wherein the receiver is further configured to use the calculated cross-correlation function between the signal received over the given channel and the reference version of the given navigation signal to determine a code-phase alignment between the received given navigation signal and the provided reference version of the given navigation signal.

5. The receiver of claim 4, wherein the code-phase alignment is dependent upon: (i) the propagation time of the given navigation signal from the satellite to the receiver and (ii) the clock bias between the receiver clock and the time reference maintained by the GLASS.

6. The receiver of claim 4, wherein the calculated cross-correlation functions used for performing the joint estimate are centered on the determined code-phase alignment for each satellite.

7. The receiver of claim 2, wherein the contributions for the one or more navigation signals include multiple non-line-of-sight components.

8. The receiver of claim 1, wherein the time-delay is referenced to arrival of a line-of-sight component.

9. The receiver of claim 1, wherein the approximate clock bias is equal to an initial estimated clock bias having a typical accuracy (1-sigma) in the range 0.1-1 microseconds.

10. The receiver of claim 1, wherein the receiver is configured to estimate the approximate clock bias, prior to performing the joint estimation, by using the calculated cross-correlation functions to determine a maximum of a composite cross-correlation function for the composite channel.

12. The receiver of claim 1, wherein performing the joint estimate of the clock bias includes searching a predefined range of possible clock bias values.

13. The receiver of claim 1, wherein the composite channel is specified by a set of coefficients, each coefficient corresponding to a particular time-delay, and representing the aggregate level of power transmission through the composite channel for that time-delay.

14. The receiver of claim 13, wherein the receiver includes at least one probability distribution function for each coefficient in the set of coefficients.

15. The receiver of claim 14, wherein the provided probability distribution functions are based on an estimate of the composite channel obtained using received signals from a previous epoch.

16. The receiver of claim 15, wherein the receiver is configured to update the probability distribution functions based on the estimated composite channel.

17. The receiver of claim 14, wherein receiver performs the joint estimate using a Monte Carlo search based on trial values of the composite channel, generated in accordance with the probability density functions, to find the trial values and clock bias that best fit the calculated cross-correlation functions.

19. The receiver of claim 1, wherein the receiver includes multiple antennas, and the joint estimate takes advantage of spatial correlation between the signals received by different antennas.

21. The receiver of claim 1, wherein the estimated clock bias has an accuracy of less than 100 nanoseconds.

23. The method of claim 22, wherein the receiver is located in an indoor environment.